Oxidation reactions of N,N-benzylalkylamines by [WO(O2)2OCOC5H4N]-[Bu4N+] to nitrones were kinetically studied by UV and EPR techniques. The reactions follow a second-order rate law and the rate-determining step is a simple bimolecular attack of amine onto the peroxide oxygen of the peroxometal complex, which leads to the formation of the corresponding hydroxylamine. However, EPR measurements and iterative procedures point out that the reaction occurs through the intermediacy of aminoxyl radicals, formed by oxidation of hydroxylamine generated in situ in the rate-determining step, and subsequent oxidations of these radicals to nitrones by the starting peroxo complex. It is suggested that the oxidation of hydroxylamine to aminoxyl radical as well as the oxidation of aminoxyl radical to nitrone occurs through an electron transfer step associated with a proton transfer.
Oxidation reactions of N,N-benzylalkylamines by [WO(O2)2OCOC5H4N]-[Bu4N+] to nitrones were kineticallystudied by UV and EPR techniques. The reactions follow a second-order rate law and the rate-determiningstep is a simple bimolecular attack of amine onto the peroxide oxygen of the peroxometal complex, whichleads to the formation of the corresponding hydroxylamine. However, EPR measurements and iterativeprocedures point out that the reaction occurs through the intermediacy of aminoxyl radicals, formed by oxidationof hydroxylamine generated in situ in the rate-determining step, and subsequent oxidations of these radicalsto nitrones by the starting peroxo complex. It is suggested that the oxidation of hydroxylamine to aminoxylradical as well as the oxidation of aminoxyl radical to nitrone occurs through an electron transfer step associatedwith a proton transfer.
EPR Kinetic evidence for radical intermediacy in the oxidation of secondary amines to nitrones by [WO(O2)2OCOC5H4N]-[Bu4N+]
BALLISTRERI, Francesco Paolo;TOMASELLI, Gaetano;TOSCANO, Rosa Maria
2000-01-01
Abstract
Oxidation reactions of N,N-benzylalkylamines by [WO(O2)2OCOC5H4N]-[Bu4N+] to nitrones were kineticallystudied by UV and EPR techniques. The reactions follow a second-order rate law and the rate-determiningstep is a simple bimolecular attack of amine onto the peroxide oxygen of the peroxometal complex, whichleads to the formation of the corresponding hydroxylamine. However, EPR measurements and iterativeprocedures point out that the reaction occurs through the intermediacy of aminoxyl radicals, formed by oxidationof hydroxylamine generated in situ in the rate-determining step, and subsequent oxidations of these radicalsto nitrones by the starting peroxo complex. It is suggested that the oxidation of hydroxylamine to aminoxylradical as well as the oxidation of aminoxyl radical to nitrone occurs through an electron transfer step associatedwith a proton transfer.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
